The Desmoteplase in Acute Ischemic Stroke Trial (DIAS): a phase II MRI-based 9-hour window acute stroke thrombolysis trial with intravenous desmoteplase

The POST trial: initial post-market experience of the Penumbra system: revascularization of large vessel occlusion in acute ischemic stroke in the United States and Europe

Background and purpose

The purpose of this study was to assess the initial post-market experience of the device and how it is compared with the Penumbra Pivotal trial used to support the 510k application.

Methods

A retrospective case review of 157 consecutive patients treated with the Penumbra system at seven international centers was performed. Primary endpoints were revascularization of the target vessel (TIMI score of 2 or 3), good functional outcome as defined by a modified Rankin scale (mRS) score of ≤2 and incidence of procedural serious adverse events. Results were compared with those of the Penumbra pivotal trial.

Results

A total of 157 vessels were treated. Mean baseline values at enrollment were: age 65 years, NIHSS score 16. After use of the Penumbra system, 87% of the treated vessels were revascularized to TIMI 2 (54%) or 3 (33%) as compared with 82% reported in the Pivotal trial. Nine procedural serious adverse events were reported in 157 patients (5.7%). All-cause mortality was 20% (32/157), and 41% had a mRS of ≤2 at 90-day follow-up as compared with only 25% in the Pivotal trial. Patients who were successfully revascularized by the Penumbra system had significantly better outcomes than those who were not.

Conclusion

Initial post-market experience of the Penumbra system revealed that the revascularization rate and safety profile of the device are comparable to those reported in the Pivotal trial. However, the proportion of patients who had good functional outcome was higher than expected.

Different doses of tenecteplase vs alteplase in thrombolysis therapy of acute ischemic stroke: evidence from randomized controlled trials

Background

Recent studies showed inconsistent results of tenecteplase vs alteplase for acute ischemic stroke (AIS) with safety and efficacy.

Methods

A meta-analysis was performed to explore the value of tenecteplase and alteplase in AIS treatment. Medline, Embase, and Cochrane Library from January 2001 to April 2018 were searched for randomized controlled trials (RCTs) with tenecteplase vs alteplase for AIS.

Results

The primary outcomes were early neurological improvement at 24 h and functional outcome at 3 months. We pooled 1,390 patients from four RCTs. Tenecteplase showed a significant early neurological improvement (P=0.035) compared with alteplase. In addition, tenecteplase showed a neutral effect on excellent outcome (P=0.309), good functional outcome (P=0.275), and recanalization (P=0.3). No significant differences in safety outcomes were demonstrated. In subgroup analysis, 0.25 mg/kg dose of tenecteplase showed a significantly increased early neurological improvement (P<0.001). In serious stroke at baseline (National Institutes of Health Stroke Scale [NIHSS] >12) subgroup, tenecteplase showed a dramatic early neurological improvement (P=0.002) and low risks of any intracranial hemorrhage (ICH) (P=0.027).

Conclusion

Tenecteplase provided better early neurological improvement than alteplase. The 0.25 mg/kg dose of tenecteplase subgroup specially showed better early neurological improvement and lower any ICH tendency than that of alteplase. In addition, in serious stroke at baseline subgroup, tenecteplase showed a lower risk of any ICH.

Update in the Early Management and Reperfusion Strategies of Patients with Acute Ischemic Stroke

Acute ischemic stroke (AIS) remains a leading cause of death and long-term disability. The paradigms on prehospital care, reperfusion therapies, and postreperfusion management of patients with AIS continue to evolve. After the publication of pivotal clinical trials, endovascular thrombectomy has become part of the standard of care in selected cases of AIS since 2015. New stroke guidelines have been recently published, and the time window for mechanical thrombectomy has now been extended up to 24 hours. This review aims to provide a focused up-to-date review for the early management of adult patients with AIS and introduce the new upcoming areas of ongoing research.

Intravenous thrombolysis for acute ischemic stroke: a bridge between two centuries

INTRODUCTION

Intravenous tissue-plasminogen activator (tPA) remains the only approved systemic reperfusion therapy suitable for most patients presenting timely with acute ischemic stroke. Accumulating real-word experience for over 20 years regarding tPA safety and effectiveness led to re-appraisal of original contraindications for intravenous thrombolysis (IVT). Areas covered: This narrative review focuses on fast yet appropriate selection of patients for safe administration of tPA per recently expanded indications. Novel strategies for rapid patient assessment will be discussed. The potential for mobile stroke units (MSU) that shorten onset-to-needle time and increase tPA treatment rates is addressed. The use of IVT in the era of non-vitamin K antagonist oral anticoagulants (NOACs) is highlighted. The continuing role of IVT in large vessel occlusion (LVO) patients eligible for mechanical thrombectomy (MT) is discussed with regards to 'drip and ship' vs. 'mothership' treatment paradigms. Promising studies of penumbral imaging to extend IVT beyond the 4.5-hour window and in wake-up strokes are summarized. Expert commentary: This review provides an update on the role of IVT in specific conditions originally considered tPA contraindications. Novel practice challenges including NOAC's, MSU proliferation and bridging therapy (IVT&MT) for LVO patients, and the potential extension of IVT time-window using penumbral imaging are emerging as safe and potentially effective IVT applications.

Reconstruction-of-difference (RoD) imaging for cone-beam CT neuro-angiography

Timely evaluation of neurovasculature via CT angiography (CTA) is critical to the detection of pathology such as ischemic stroke. Cone-beam CTA (CBCT-A) systems provide potential advantages in the timely use at the point-of-care, although challenges of a relatively slow gantry rotation speed introduce tradeoffs among image quality, data consistency and data sparsity. This work describes and evaluates a new reconstruction-of-difference (RoD) approach that is robust to such challenges. A fast digital simulation framework was developed to test the performance of the RoD over standard reference reconstruction methods such as filtered back-projection (FBP) and penalized likelihood (PL) over a broad range of imaging conditions, grouped into three scenarios to test the trade-off between data consistency, data sparsity and peak contrast. Two experiments were also conducted using a CBCT prototype and an anthropomorphic neurovascular phantom to test the simulation findings in real data. Performance was evaluated primarily in terms of normalized root mean square error (NRMSE) in comparison to truth, with reconstruction parameters chosen to optimize performance in each case to ensure fair comparison. The RoD approach reduced NRMSE in reconstructed images by up to 50%-53% compared to FBP and up to 29%-31% compared to PL for each scenario. Scan protocols well suited to the RoD approach were identified that balance tradeoffs among data consistency, sparsity and peak contrast-for example, a CBCT-A scan with 128 projections acquired in 8.5 s over a 180°  +  fan angle half-scan for a time attenuation curve with ~8.5 s time-to-peak and 600 HU peak contrast. With imaging conditions such as the simulation scenarios of fixed data sparsity (i.e. varying levels of data consistency and peak contrast), the experiments confirmed the reduction of NRMSE by 34% and 17% compared to FBP and PL, respectively. The RoD approach demonstrated superior performance in 3D angiography compared to FBP and PL in all simulation and physical experiments, suggesting the possibility of CBCT-A on low-cost, mobile imaging platforms suitable to the point-of-care. The algorithm demonstrated accurate reconstruction with a high degree of robustness against data sparsity and inconsistency.

Neuroimaging Paradigms to Identify Patients for Reperfusion Therapy in Stroke of Unknown Onset

Despite the proven efficacy of intravenous alteplase or endovascular thrombectomy for the treatment of patients with acute ischemic stroke, only a minority receive these treatments. This low treatment rate is due in large part to delay in hospital arrival or uncertainty as to the exact time of onset of ischemic stroke, which renders patients outside the current guideline-recommended window of eligibility for receiving these therapeutics. However, recent pivotal clinical trials of late-window thrombectomy now force us to rethink the value of a simplistic chronological formulation that “time is brain.” We must recognize a more nuanced concept that the rate of tissue death as a function of time is not invariant, that still salvageable tissue at risk of infarction may be present up to 24 h after last-known well, and that those patients may strongly benefit from reperfusion. Multiple studies have sought to address this clinical dilemma using neuroimaging methods to identify a radiographic time-stamp of stroke onset or evidence of salvageable ischemic tissue and thereby increase the number of patients eligible for reperfusion therapies. In this review, we provide a critical analysis of the current state of neuroimaging techniques to select patients with unwitnessed stroke for revascularization therapies and speculate on the future direction of this clinically relevant area of stroke research.

ACR Appropriateness Criteria® Cerebrovascular Disease

Diseases of the cerebral vasculature represent a heterogeneous group of ischemic and hemorrhagic etiologies, which often manifest clinically as an acute neurologic deficit also known as stroke or less commonly with symptoms such as headache or seizures. Stroke is the fourth leading cause of death and is a leading cause of serious long-term disability in the United States. Eighty-seven percent of strokes are ischemic, 10% are due to intracerebral hemorrhage, and 3% are secondary to subarachnoid hemorrhage. The past two decades have seen significant developments in the screening, diagnosis, and treatment of ischemic and hemorrhagic causes of stroke with advancements in CT and MRI technology and novel treatment devices and techniques. Multiple different imaging modalities can be used in the evaluation of cerebrovascular disease. The different imaging modalities all have their own niches and their own advantages and disadvantages in the evaluation of cerebrovascular disease. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Perfluorocarbon Enhanced Glasgow Oxygen Level Dependent (GOLD) Magnetic Resonance Metabolic Imaging Identifies the Penumbra Following Acute Ischemic Stroke

The ability to identify metabolically active and potentially salvageable ischaemic penumbra is crucial for improving treatment decisions in acute stroke patients. Our solution involves two complementary novel MRI techniques (Glasgow Oxygen Level Dependant (GOLD) Metabolic Imaging), which when combined with a perfluorocarbon (PFC) based oxygen carrier and hyperoxia can identify penumbra due to dynamic changes related to continued metabolism within this tissue compartment. Our aims were (i) to investigate whether PFC offers similar enhancement of the second technique (Lactate Change) as previously demonstrated for the T₂*OC technique (ii) to demonstrate both GOLD metabolic imaging techniques working concurrently to identify penumbra, following administration of Oxycyte^® (O-PFC) with hyperoxia.

Methods: An established rat stroke model was utilised. Part-1: Following either saline or PFC, magnetic resonance spectroscopy was applied to investigate the effect of hyperoxia on lactate change in presumed penumbra. Part-2; rats received O-PFC prior to T₂*OC (technique 1) and MR spectroscopic imaging, which was used to identify regions of tissue lactate change (technique 2) in response to hyperoxia. In order to validate the techniques, imaging was followed by [¹⁴C]2-deoxyglucose autoradiography to correlate tissue metabolic status to areas identified as penumbra.

Results: Part-1: PFC+hyperoxia resulted in an enhanced reduction of lactate in the penumbra when compared to saline+hyperoxia. Part-2: Regions of brain tissue identified as potential penumbra by both GOLD metabolic imaging techniques utilising O-PFC, demonstrated maintained glucose metabolism as compared to adjacent core tissue.

Conclusion: For the first time in vivo, enhancement of both GOLD metabolic imaging techniques has been demonstrated following intravenous O-PFC+hyperoxia to identify ischaemic penumbra. We have also presented preliminary evidence of the potential therapeutic benefit offered by O-PFC. These unique theranostic applications would enable treatment based on metabolic status of the brain tissue, independent of time from stroke onset, leading to increased uptake and safer use of currently available treatment options.

2018 Guidelines for the Early Management of Patients With Acute Ischemic Stroke: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association

BACKGROUND AND PURPOSE

The purpose of these guidelines is to provide an up-to-date comprehensive set of recommendations for clinicians caring for adult patients with acute arterial ischemic stroke in a single document. The intended audiences are prehospital care providers, physicians, allied health professionals, and hospital administrators. These guidelines supersede the 2013 guidelines and subsequent updates.

METHODS

Members of the writing group were appointed by the American Heart Association Stroke Council's Scientific Statements Oversight Committee, representing various areas of medical expertise. Strict adherence to the American Heart Association conflict of interest policy was maintained. Members were not allowed to participate in discussions or to vote on topics relevant to their relations with industry. The members of the writing group unanimously approved all recommendations except when relations with industry precluded members voting. Prerelease review of the draft guideline was performed by 4 expert peer reviewers and by the members of the Stroke Council's Scientific Statements Oversight Committee and Stroke Council Leadership Committee. These guidelines use the American College of Cardiology/American Heart Association 2015 Class of Recommendations and Levels of Evidence and the new American Heart Association guidelines format.

RESULTS

These guidelines detail prehospital care, urgent and emergency evaluation and treatment with intravenous and intra-arterial therapies, and in-hospital management, including secondary prevention measures that are appropriately instituted within the first 2 weeks. The guidelines support the overarching concept of stroke systems of care in both the prehospital and hospital settings.

CONCLUSIONS

These guidelines are based on the best evidence currently available. In many instances, however, only limited data exist demonstrating the urgent need for continued research on treatment of acute ischemic stroke.

Reperfusion therapy in acute ischemic stroke: dawn of a new era?

Following the success of recent endovascular trials, endovascular therapy has emerged as an exciting addition to the arsenal of clinical management of patients with acute ischemic stroke (AIS). In this paper, we present an extensive overview of intravenous and endovascular reperfusion strategies, recent advances in AIS neurointervention, limitations of various treatment paradigms, and provide insights on imaging-guided reperfusion therapies. A roadmap for imaging guided reperfusion treatment workflow in AIS is also proposed. Both systemic thrombolysis and endovascular treatment have been incorporated into the standard of care in stroke therapy. Further research on advanced imaging-based approaches to select appropriate patients, may widen the time-window for patient selection and would contribute immensely to early thrombolytic strategies, better recanalization rates, and improved clinical outcomes.

Slice-accelerated gradient-echo echo planar imaging dynamic susceptibility contrast-enhanced MRI with blipped CAIPI: effect of increasing temporal resolution

PURPOSE

To assess the influence of high temporal resolution on the perfusion measurements and image quality of perfusion maps, by applying simultaneous-multi-slice acquisition (SMS) dynamic susceptibility contrast-enhanced (DSC) magnetic resonance imaging (MRI).

MATERIALS AND METHODS

DSC-MRI data using SMS gradient-echo echo planar imaging sequences in 10 subjects with no intracranial abnormalities were retrospectively analyzed. Three additional data sets with temporal resolution of 1.0, 1.5, and 2.0 s were created from the raw data sets of 0.5 s. Cerebral blood flow (CBF), cerebral blood volume, mean transit time (MTT), time to peak (TTP), and time to maximum tissue residue function (T _max) measurements were performed, as was visual perfusion map analysis. The perfusion parameter for temporal resolution of 0.5 s (reference) was compared with each synthesized perfusion parameter.

RESULTS

CBF, MTT, and TTP values at temporal resolutions of 1.5 and 2.0 s differed significantly from the reference. The image quality of MTT, TTP, and T _max maps deteriorated with decreasing temporal resolution.

CONCLUSION

The temporal resolution of DSC-MRI influences perfusion parameters and SMS DSC-MRI provides better image quality for MTT, TTP, and T _max maps.

Incorporation of relative cerebral blood flow into CT perfusion maps reduces false ’at risk' penumbra

Purpose

The region defined as ‘at risk’ penumbra by current CT perfusion (CTP) maps is largely overestimated. We aimed to quantitate the portion of true ‘at risk’ tissue within CTP penumbra and to determine the parameter and threshold that would optimally distinguish it from false ‘at risk’ tissue, that is, benign oligaemia.

Methods

Among acute stroke patients evaluated by multimodal CT (NCCT/CTA/CTP) we identified those that had not undergone endovascular/thrombolytic treatment and had follow-up NCCT. Maps of absolute and relative CBF, CBV, MTT, TTP and Tmax as well as summary maps depicting infarcted and penumbral regions were generated using the Intellispace Portal (Philips Healthcare, Best, Netherlands). Follow-up CT was automatically co-registered to the CTP scan and the final infarct region was manually outlined. Perfusion parameters were systematically analysed – the parameter that resulted in the highest true-negative-rate (ie, proportion of benign oligaemia correctly identified) at a fixed, clinically relevant false-negative-rate (ie, proportion of ‘missed’ infarct) of 15%, was chosen as optimal. It was then re-applied to the CTP data to produce corrected perfusion maps.

Results

Forty seven acute stroke patients met selection criteria. Average portion of infarcted tissue within CTP penumbra was 15%±2.2%. Relative CBF at a threshold of 0.65 yielded the highest average true-negative-rate (48%), enabling reduction of the false ‘at risk’ penumbral region by ~half.

Conclusions

Applying a relative CBF threshold on relative MTT-based CTP maps can significantly reduce false ‘at risk’ penumbra. This step may help to avoid unnecessary endovascular interventions.

Quantifying reperfusion of the ischemic region on whole-brain computed tomography perfusion

To derive the reperfusion index best predicting clinical outcome of ischemic stroke patients, we retrospectively analysed the acute and 24-h computed tomography perfusion data of 116 patients, collected from two centres equipped with whole-brain computed tomography perfusion. Reperfusion index was defined by the percentage of the ischemic region reperfused from acute to 24-h computed tomography perfusion. Recanalization was graded by arterial occlusive lesion system. Receiver operator characteristic analysis was performed to assess the prognostic value of reperfusion and recanalization in predicting good clinical outcome, defined as modified Rankin Score of 0-2 at 90 days. Among previous reported reperfusion measurements, reperfusion of the Tmax>6 s region resulted in higher prognostic value than recanalization at predicting good clinical outcome (area under the curve = 0.88 and 0.74, respectively, p = 0.002). Successful reperfusion of the Tmax>6 s region (≥60%) had 89% sensitivity and 78% specificity in predicting good clinical outcome. A reperfusion index defined by Tmax>2 s or by mean transit time>145% had much lower area under the curve in comparison to Tmax>6 s measurement (p < 0.001 and p = 0.003, respectively), and had no significant difference to recanalization at predicting clinical outcome (p = 0.58 and 0.63, respectively). In conclusion, reperfusion index calculated by Tmax>6 s is a stronger predictor of clinical outcome than recanalization or other reperfusion measures.

European Cooperative Acute Stroke Study-4: Extending the time for thrombolysis in emergency neurological deficits ECASS-4: ExTEND

RATIONALE AND HYPOTHESIS

Thrombolytic therapy with recombinant tissue plasminogen activator (rt-PA) is an effective and approved therapy for acute ischemic stroke within 4.5 h of onset except for USA, Canada, Croatia, and Moldovia with a current 3 h label. We hypothesized that ischemic stroke patients selected with significant penumbral mismatch on magnetic resonance imaging (MRI) at 4.5-9 h after onset of stroke will have improved clinical outcomes when given intravenous rt-PA (alteplase) compared to placebo.

STUDY DESIGN

ECASS-4: ExTEND is an investigator driven, phase 3, randomized, multi-center, double-blind, placebo-controlled study. Ischemic stroke patients presenting within 4.5 and 9 h of stroke onset, who fulfil clinical requirements (National Institutes of Health Stroke Score (NIHSS) 4-26 and pre-stroke modified Rankin Scale (mRS) 0-1) will undergo MRI. Patients who meet imaging criteria (infarct core volume <100 ml, perfusion lesion: infarct core mismatch ratio >1.2 and perfusion lesion minimum volume of 20 ml) additionally will be randomized to either rt-PA or placebo.

STUDY OUTCOME

The primary outcome measure will be the categorical shift in the mRS at day 90. Clinical secondary outcomes will be disability at day 90 dichotomized as favorable outcome mRS 0-1 at day 90. Tertiary endpoints include reduction in the NIHSS by 11 or more points or reaching 0-1 at day 90, reperfusion and recanalization at 24 h post stroke as well as depression, life quality, and cognitive impairment at day 90. Safety endpoints will include symptomatic intracranial hemorrhage (ICH) and death.

Efficacy and safety of desmoteplase in acute ischemic stroke patients: A systematic review and meta-analysis

BACKGROUND

Pending results from double-blind, multicenter, parallel-group, randomized trials, the benefit and safety of the novel plasminogen activator, desmoteplase remain undetermined. The aim of this meta-analysis was to help evaluate desmoteplase's efficacy and safety.

METHODS

A thorough search was performed of the Cochrane Library, PubMed, and Embase from the inception of electronic data to March 2017, and double-blind, multicenter, parallel-group, randomized trials were chosen. We conducted a meta-analysis of studies investigating intravenous desmoteplase treatment of acute ischemic stroke patients 3 to 9 hours after symptom onset. Asymptomatic intracerebral hemorrhage, good clinical outcome at 90 days, and reperfusion 4 to 8 hours posttreatment were variables assessing efficacy; symptomatic intracerebral hemorrhage and death rates were measures of safety.

RESULTS

Six trials involving 1071 patients thrombolyzed >3 hours postonset were included (600 received intravenous desmoteplase, 471 placebo). Desmoteplase was associated with increased reperfusion (odds ratio [OR] 1.57; 95% confidence interval [CI], 1.10-2.24; P = .01 vs control) and showed a tendency to increase asymptomatic intracerebral hemorrhage (OR 1.25; 95% CI, 0.97-1.62; P = .09 vs control), whereas there was no increase in symptomatic intracerebral hemorrhage and death rate with desmoteplase. However, there was no difference in the clinical response at 90 days (OR 1.14; 95% CI, 0.88-1.49; P = .31 vs control). Subgroup analysis showed that desmoteplase 90 μg/kg (OR 1.53; 95% CI, 1.07-2.21; P = .02 vs control) and 125 μg/kg (OR 4.07; 95% CI, 1.16-14.24; P = .03 vs control) were associated with an increase in reperfusion. Also, we found desmoteplase 90 μg/kg showed a tendency to increase asymptomatic intracerebral hemorrhage (OR 1.25; 95% CI, 0.95-1.63; P = .11 vs control).

CONCLUSION

Intravenous desmoteplase is associated with a favorable reperfusion efficacy and acceptable safety in ischemic stroke treatment >3 hours after symptom onset. Well-designed randomized controlled trials with larger patient cohorts and a moderate dose of drugs are needed to further evaluate the true efficacy of desmoteplase in stroke patients.

TRIAL REGISTRATION

URL: http://www.crd.york.ac.uk/PROSPERO; PROSPERO registration number: CRD42016037667).

A first-in-human study of DS-1040, an inhibitor of the activated form of thrombin-activatable fibrinolysis inhibitor, in healthy subjects

Essentials DS-1040 inhibits the activated form of thrombin-activatable fibrinolysis inhibitor (TAFIa). Infusion of DS-1040 was safe and well tolerated in healthy young and elderly subjects. DS-1040 substantially decreased TAFIa activity but had no impact on bleeding time. DS-1040 may provide an option of safer thrombolytic therapy.

SUMMARY

Background Current treatments for acute ischemic stroke and venous thromboembolism, such as recombinant tissue-type plasminogen activator and thrombectomy, are limited by a narrow time window and the risk of bleeding. DS-1040 is a novel low molecular weight compound that inhibits the activated form of thrombin-activatable fibrinolysis inhibitor (TAFIa), and was developed as a fibrinolysis enhancer for the treatment of thromboembolic diseases. Objectives This first-in-human, randomized, placebo-controlled, three-part, phase 1 study was conducted to evaluate the safety, pharmacokinetics and pharmacodynamics of DS-1040 in healthy subjects. Subjects/Methods Young (18-45 years) or elderly (65-75 years) subjects (N = 103) were randomized to receive single ascending doses of DS-1040 ranging from 0.1 mg to 40 mg, or placebo, administered either as a 0.5-h intravenous infusion or as a 24-h continuous infusion. Results All doses of DS-1040 were tolerated, and no serious adverse events (AEs) or discontinuations resulting from AEs occurred during the study. Bleeding time remained within the normal range for all doses tested in all subjects. Plasma exposure of DS-1040 increased proportionally with increase in dose. Elderly subjects had higher exposures to DS-1040 and prolonged elimination times, probably because of decreased renal clearance. DS-1040 caused a substantial dose-dependent and time-dependent decrease in TAFIa activity and in 50% clot lysis time. The levels of D-dimer, indicative of endogenous fibrinolysis, increased in some individuals following DS-1040 treatment. No effects of DS-1040 on coagulation parameters or platelet aggregation were observed. Conclusions The novel fibrinolysis-enhancing agent DS-1040 has favorable pharmacokinetic/pharmacodynamic properties and a favorable safety profile, warranting further clinical development.

Endogenous regeneration: Engineering growth factors for stroke

Despite the efforts in developing therapeutics for stroke, recombinant tissue plasminogen activator (rtPA) remains the only FDA approved drug for ischemic stroke. Regenerative medicine targeting endogenous growth factors has drawn much interest in the clinical field as it provides potential restoration for the damaged brain tissue without being limited by a narrow therapeutic window. To date, most of the translational studies using regenerative medicines have encountered problems and failures. In this review, we discuss the effects of some trophic factors which include of erythropoietin (EPO), brain derived neurotrophic factor (BDNF), granulocyte-colony stimulating factor (G-CSF), vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), epidermal growth factor (EGF) and heparin binding epidermal growth factor (HB-EGF) in experimental ischemic stroke models and elaborate the lost in translation of the candidate growth factors from bench to bedside. Several new methodologies have been developed to overcome the caveats in translational studies. This review highlights the latest bioengineering approaches including the controlled release and delivery of growth factors by hydrogel-based scaffolds and the enhancement of half-life and selectivity of growth factors by a novel approach facilitated by glycosaminoglycans.

Understanding the Neurophysiology and Quantification of Brain Perfusion

Newer neuroimaging technology has moved beyond pure anatomical imaging and ventured into functional and physiological imaging. Perfusion magnetic resonance imaging (PWI), which depicts hemodynamic conditions of the brain at the microvascular level, has an increasingly important role in clinical central nervous system applications. This review provides an overview of the established role of PWI in brain tumor and cerebrovascular imaging, as well as some emerging applications in neuroimaging. PWI allows better characterization of brain tumors, grading, and monitoring. In acute stroke imaging, PWI is utilized to distinguish penumbra from infarcted tissue. PWI is a promising tool in the assessment of neurodegenerative and neuropsychiatric diseases, although its clinical role is not yet defined.

Biochemical changes in the injured brain

Brain metabolism is an energy intensive phenomenon involving a wide spectrum of chemical intermediaries. Various injury states have a detrimental effect on the biochemical processes involved in the homeostatic and electrophysiological properties of the brain. The biochemical markers of brain injury are a recent addition in the armamentarium of neuro-clinicians and are being increasingly used in the routine management of neuro-pathological entities such as traumatic brain injury, stroke, subarachnoid haemorrhage and intracranial space occupying lesions. These markers are increasingly being used in assessing severity as well as in predicting the prognostic course of neuro-pathological lesions. S-100 protein, neuron specific enolase, creatinine phosphokinase isoenzyme BB and myelin basic protein are some of the biochemical markers which have been proven to have prognostic and clinical value in the brain injury. While S-100, glial fibrillary acidic protein and ubiquitin C terminal hydrolase are early biomarkers of neuronal injury and have the potential to aid in clinical decision-making in the initial management of patients presenting with an acute neuronal crisis, the other biomarkers are of value in predicting long-term complications and prognosis in such patients. In recent times cerebral microdialysis has established itself as a novel way of monitoring brain tissue biochemical metabolites such as glucose, lactate, pyruvate, glutamate and glycerol while small non-coding RNAs have presented themselves as potential markers of brain injury for future.

Acute Ischemic Stroke Therapy Overview

The treatment of acute ischemic stroke has undergone dramatic changes recently subsequent to the demonstrated efficacy of intra-arterial (IA) device-based therapy in multiple trials. The selection of patients for both intravenous and IA therapy is based on timely imaging with either computed tomography or magnetic resonance imaging, and if IA therapy is considered noninvasive, angiography with one of these modalities is necessary to document a large-vessel occlusion amenable for intervention. More advanced computed tomography and magnetic resonance imaging studies are available that can be used to identify a small ischemic core and ischemic penumbra, and this information will contribute increasingly in treatment decisions as the therapeutic time window is lengthened. Intravenous thrombolysis with tissue-type plasminogen activator remains the mainstay of acute stroke therapy within the initial 4.5 hours after stroke onset, despite the lack of Food and Drug Administration approval in the 3- to 4.5-hour time window. In patients with proximal, large-vessel occlusions, IA device-based treatment should be initiated in patients with small/moderate-sized ischemic cores who can be treated within 6 hours of stroke onset. The organization and implementation of regional stroke care systems will be needed to treat as many eligible patients as expeditiously as possible. Novel treatment paradigms can be envisioned combining neuroprotection with IA device treatment to potentially increase the number of patients who can be treated despite long transport times and to ameliorate the consequences of reperfusion injury. Acute stroke treatment has entered a golden age, and many additional advances can be anticipated.

Treatment of Acute Ischemic Stroke

Although stroke declined from the third to fifth most common cause of death in the United States, the annual incidence and overall prevalence continue to increase. Since the available US Food and Drug Administration-approved treatment options are time dependent, improving early stroke care may have more of a public health impact than any other phase of care. Timely and efficient stroke treatment should be a priority for emergency department and prehospital providers. This article discusses currently available and emerging treatment options in acute ischemic stroke focusing on the preservation of salvageable brain tissue, minimizing complications, and secondary prevention.

Arterial Obstruction on Computed Tomographic or Magnetic Resonance Angiography and Response to Intravenous Thrombolytics in Ischemic Stroke

BACKGROUND AND PURPOSE

Computed tomographic angiography and magnetic resonance angiography are used increasingly to assess arterial patency in patients with ischemic stroke. We determined which baseline angiography features predict response to intravenous thrombolytics in ischemic stroke using randomized controlled trial data.

METHODS

We analyzed angiograms from the IST-3 (Third International Stroke Trial), an international, multicenter, prospective, randomized controlled trial of intravenous alteplase. Readers, masked to clinical, treatment, and outcome data, assessed prerandomization computed tomographic angiography and magnetic resonance angiography for presence, extent, location, and completeness of obstruction and collaterals. We compared angiography findings to 6-month functional outcome (Oxford Handicap Scale) and tested for interactions with alteplase, using ordinal regression in adjusted analyses. We also meta-analyzed all available angiography data from other randomized controlled trials of intravenous thrombolytics.

RESULTS

In IST-3, 300 patients had prerandomization angiography (computed tomographic angiography=271 and magnetic resonance angiography=29). On multivariable analysis, more extensive angiographic obstruction and poor collaterals independently predicted poor outcome (P<0.01). We identified no significant interaction between angiography findings and alteplase effect on Oxford Handicap Scale (P≥0.075) in IST-3. In meta-analysis (5 trials of alteplase or desmoteplase, including IST-3, n=591), there was a significantly increased benefit of thrombolytics on outcome (odds ratio>1 indicates benefit) in patients with (odds ratio, 2.07; 95% confidence interval, 1.18-3.64; P=0.011) versus without (odds ratio, 0.88; 95% confidence interval, 0.58-1.35; P=0.566) arterial obstruction (P for interaction 0.017).

CONCLUSIONS

Intravenous thrombolytics provide benefit to stroke patients with computed tomographic angiography or magnetic resonance angiography evidence of arterial obstruction, but the sample was underpowered to demonstrate significant treatment benefit or harm among patients with apparently patent arteries.

CLINICAL TRIAL REGISTRATION

URL: http://www.isrctn.com. Unique identifier: ISRCTN25765518.

Investigating potentially salvageable penumbra tissue in an in vivo model of transient ischemic stroke using sodium, diffusion, and perfusion magnetic resonance imaging

BACKGROUND

Diffusion magnetic resonance imaging (MRI) is the current-state-of-the-art technique to clinically investigate acute (0-24 h) ischemic stroke tissue. However, reduced apparent diffusion coefficient (ADC)-considered a marker of tissue damage-was observed to reverse spontaneously during the subacute stroke phase (24-72 h) which means that low ADC cannot be used to reflect the damaged tissue after 24 h in experimental and clinical studies. One reason for the change in ADC is that ADC values drop with cytotoxic edema (acute phase) and rise when vasogenic edema begins (subacute phase). Recently, combined ¹H- and ²³Na-MRI was proposed as a more accurate approach to improve delineation between reversible (penumbra) and irreversible ischemic injury (core). The aim of this study was to investigate the effects of reperfusion on the ADC and the sodium MRI signal after experimental ischemic stroke in rats in well-defined areas of different viability levels of the cerebral lesion, i.e. core and penumbra as defined via perfusion and histology. Transient middle cerebral artery occlusion was induced in male rats by using the intraluminal filament technique. MRI sodium, perfusion and diffusion measurement was recorded before reperfusion, shortly after reperfusion and 24 h after reperfusion. The animals were reperfused after 90 min of ischemia.

RESULTS

Sodium signal in core did not change before reperfusion, increased after reperfusion while sodium signal in penumbra was significantly reduced before reperfusion, but showed no changes after reperfusion compared to control. The ADC was significantly decreased in core tissue at all three time points compared to contralateral side. This decrease recovered above commonly applied viability thresholds in the core after 24 h.

CONCLUSIONS

Reduced sodium-MRI signal in conjunction with reduced ADC can serve as a viability marker for penumbra detection and complement hydrogen diffusion- and perfusion-MRI in order to facilitate time-independent assessment of tissue fate and cellular bioenergetics failure in stroke patients.

Desmoteplase 3 to 9 Hours After Major Artery Occlusion Stroke

Background and Purpose—

The DIAS-3 trial (Efficacy and Safety Study of Desmoteplase to Treat Acute Ischemic Stroke [phase 3]) did not demonstrate a significant clinical benefit of desmoteplase administered 3 to 9 hours after stroke in patients with major artery occlusion. We present the results of the prematurely terminated DIAS-4 trial together with a post hoc pooled analysis of the concomitant DIAS-3, DIAS-4, and DIAS-J (Japan) trials to better understand the potential risks and benefits of intravenous desmoteplase for the treatment of ischemic stroke in an extended time window.

Methods—

Ischemic stroke patients with occlusion/high-grade stenosis in major cerebral arteries were randomly assigned to intravenous treatment with desmoteplase (90 μg/kg) or placebo. The primary outcome was modified Rankin Scale (mRS) score of 0 to 2 at day 90. Safety assessments included mortality, symptomatic intracranial hemorrhage, and other serious adverse events.

Results—

In DIAS-4, 52 of 124 (41.9%) desmoteplase-treated and 46 of 128 (35.9%) placebo-treated patients achieved an mRS score of 0 to 2 (odds ratio, 1.45; 95% confidence interval, 0.79; 2.64; P =0.23) with equal mortality, frequency of symptomatic intracranial hemorrhage, and other serious adverse events in both the treatment arms. In the pooled analysis, mRS score of 0 to 2 was achieved by 184 of 376 (48.9%) desmoteplase-treated versus 171 of 381 (44.9%) placebo-treated patients (odds ratio, 1.33; 95% confidence interval, 0.95; 1.85; P =0.096). Treatment with desmoteplase was safe and increased the recanalization rate (107/217 [49.3%] versus 85/222 [38.3%]; odds ratio, 1.59; 95% confidence interval, 1.08–2.35; P =0.019). Recanalization was associated with favorable outcomes (mRS 0–2) at day 90 in both the treatment arms.

Conclusions—

Late treatment with intravenous 90 µg/kg desmoteplase is safe, increases arterial recanalization, but does not significantly improve functional outcome at 3 months.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00856661.

Impact of Pial Collaterals on Infarct Growth Rate in Experimental Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Cerebral infarction evolves at different rates depending on available blood flow suggesting that treatment time windows vary depending on the degree of pial collateral recruitment. This work sought to mathematically model infarct growth and determine whether infarct volume growth can be predicted by angiographic assessment of pial collateral recruitment in an experimental MCA occlusion animal model.

MATERIALS AND METHODS

Pial collateral recruitment was quantified by using DSA, acquired 15 minutes following permanent MCA occlusion in 6 canines based on a scoring system (average pial collateral score) and arterial arrival time. MR imaging-based infarct volumes were measured 60, 90, 120, 180, 240 and 1440 minutes following MCA occlusion and were parameterized in terms of the growth rate index and final infarct volume (V_Final) as V(t) = V_Final [1 - e^{(-G × t)}] (t = time). Correlations of the growth rate index and final infarct volume to the average pial collateral score and arterial arrival time were assessed by linear bivariate analysis. Correlations were used to generate asymptotic models of infarct growth for average pial collateral score or arterial arrival time values. Average pial collateral score- and arterial arrival time-based models were assessed by F tests and residual errors.

RESULTS

Evaluation of pial collateral recruitment at 15 minutes postocclusion was strongly correlated with 24-hour infarct volumes (average pial collateral score: r² = 0.96, P < .003; arterial arrival time: r² = 0.86, P < .008). Infarct growth and the growth rate index had strong and moderate linear relationships to the average pial collateral score (r² = 0.89; P < .0033) and arterial arrival time (r² = 0.69; P < .0419), respectively. Final infarct volume and the growth rate index were algebraically replaced by angiographically based collateral assessments to model infarct growth. The F test demonstrated no statistical advantage to using the average pial collateral score- over arterial arrival time-based predictive models, despite lower residual errors in the average pial collateral score-based model (P < .03).

CONCLUSIONS

In an experimental permanent MCA occlusion model, assessment of pial collaterals correlates with the infarct growth rate index and has the potential to predict asymptotic infarct volume growth.

Update on the effects of treatment with recombinant tissue-type plasminogen activator (rt-PA) in acute ischemic stroke

INTRODUCTION

Acute ischemic stroke (AIS) represents a major cause of death and disability all over the world. The recommended therapy aims at dissolving the clot to re-establish quickly the blood flow to the brain and reduce neuronal injury. Intravenous administration of recombinant tissue-type plasminogen activator (rt-PA) is clinically used with this goal.

AREAS COVERED

A description of beneficial and detrimental effects of rt-PA treatment is addressed. An overview of new therapies against AIS, such as new thrombolytics, sonolysis and sonothrombolysis, endovascular procedures, and association therapies is provided. Updates on the pathophysiological process leading to intracranial hemorrhage (ICH) is also discussed.

EXPERT OPINION

rt-PA treatment in AIS patients is beneficial to recovery outcomes. To weaken risks and improve benefits, it might be relevant to consider: i) a definitive identification of risk factors for symptomatic ICH; ii). a better organization of the health care system to reduce time-to-treatment and enhance discharge management. The pharmacological improvement of new thrombolytic drugs (such as tenecteplase and desmoteplase) targeting harmful and maximally exploiting beneficial effects might further reduce mortality and disability in AIS.

Impact of the Penumbral Pattern on Clinical Outcome in Patients with Successful Endovascular Revascularization

BACKGROUND

In patients with acute ischemic stroke, the impact of penumbral patterns on clinical outcomes after endovascular treatment (EVT) remains controversial. We aimed to establish whether penumbral patterns are associated with clinical outcome after successful recanalization with EVT while adjusting for onset to revascularization time.

MATERIALS AND METHODS

Using a web-based, multicenter, prospective stroke registry database, we identified patients with acute ischemic stroke who underwent perfusion and diffusion magnetic resonance imaging (MRI) before EVT, had anterior circulation stroke, received EVT within 12 hours of symptom onset, and had successful revascularization confirmed during EVT. Based on pretreatment MRI, patients were stratified as having a favorable or nonfavorable penumbral pattern. Onset to revascularization time was dichotomized by median value. Primary outcome was functional independence (modified Rankin Scale score ≤2) at 90 days.

FINDINGS

Among 121 eligible patients from three university hospitals, 104 (86.0%) had a favorable penumbral pattern, and the median time to revascularization was 271 minutes (interquartile range, 196-371). The functionally independent patient proportion was higher in those with a favorable penumbral pattern than in those without (53.8% versus 5.9%; P <.001), but was not different between early and late revascularization groups (49.2% versus 45.0%; P = .65). The favorable penumbral pattern was associated with functional independence after adjusting confounders (odds ratio, 23.25; 95% confidence interval: 1.58-341.99; P = .02). Time to revascularization did not modify the association (P for interaction, .53).

CONCLUSION

A favorable penumbral pattern is associated with improved functional independence in patients with endovascular revascularization, and the association was not time-dependent.

Theophylline as an add-on to thrombolytic therapy in acute ischaemic stroke (TEA-Stroke): A randomized, double-blinded, placebo-controlled, two-centre phase II study

Introduction

Early reperfusion of brain tissue at risk of injury (penumbra salvage) is crucial in treating acute ischaemic stroke. Neuroprotective agents may extend the time window for the reperfusion. The vasoactive agent theophylline redistributes the perfusion to ischaemic brain tissue and thus reduces brain damage, brain tissue oedema and mortality in animal stroke models. Furthermore, treatment with theophylline has been shown to result in considerable and rapid clinical improvement, albeit only temporary, in some stroke patients.We hypothesize that treatment with theophylline will improve the collateral supply in acute ischaemic brain tissue and thus facilitate reperfusion despite proximal vessel occlusion. The primary study objective is to evaluate whether theophylline is safe and efficient in acute ischaemic stroke patients as an add-on to thrombolytic therapy.

Methods

The TEA-Stroke Trial is a two-centre, proof of concept phase II clinical study with a randomized, double-blinded, placebo-controlled design. One hundred and twenty patients with acute ischaemic stroke and significant perfusion-diffusion mismatch, as determined by magnetic resonance imaging, are randomized 1:1 to either theophylline or placebo as an add-on to standard thrombolytic therapy.

Study outcome

The dual primary outcome measures include penumbra salvage (penumbral tissue not developing into infarcted tissue) and clinical improvement at the 24-h follow-up.

Discussion

Results from studies of theophylline in stroke animal models, clinical case series and randomized clinical trials are controversial. A Cochrane analysis from 2004 concluded that there was not enough evidence to assess whether theophylline is safe and improves outcomes in patients with acute ischaemic stroke. The TEA-Stroke Trial will clarify whether theophylline as an add-on to standard thrombolytic therapy improves penumbra salvage with a reduced risk of reperfusion damage, reduced final infarct size, and improved clinical outcome.

The evolution of recombinant thrombolytics: Current status and future directions

Cardiovascular disorders are on the rise worldwide due to alcohol abuse, obesity, hypertension, raised blood lipids, diabetes and age-related risks. The use of classical antiplatelet and anticoagulant therapies combined with surgical intervention helped to clear blood clots during the inceptive years. However, the discovery of streptokinase and urokinase ushered the way of using these enzymes as thrombolytic agents to degrade the fibrin network with an issue of systemic hemorrhage. The development of second generation plasminogen activators like anistreplase and tissue plasminogen activator partially controlled this problem. The third generation molecules, majorly t-PA variants, showed desirable properties of improved stability, safety and efficacy with enhanced fibrin specificity. Plasmin variants are produced as direct fibrinolytic agents as a futuristic approach with targeted delivery of these drugs using liposome technlogy. The novel molecules from microbial, plant and animal origin present the future of direct thrombolytics due to their safety and ease of administration.

Citation bias favoring positive clinical trials of thrombolytics for acute ischemic stroke: a cross-sectional analysis

Background

Citation bias occurs when positive trials involving a medical intervention receive more citations than neutral or negative trials of similar quality. Several large clinical trials have studied the use of thrombolytic agents for the treatment of acute ischemic stroke with differing results, thereby presenting an opportunity to assess these trials for evidence of citation bias. We compared citation rates among positive, neutral, and negative trials of alteplase (tPA) and other thrombolytic agents for stroke.

Methods

We used a 2014 Cochrane Review of thrombolytic therapy for the treatment of acute stroke to identify non-pilot, English-language stroke trials published in MEDLINE-indexed journals comparing thrombolytic therapy with control. We classified trials as positive if there was a statistically significant primary outcome difference favoring the intervention, neutral if there was no difference in primary outcome, or negative for a significant primary outcome difference favoring the control group. Trials were also considered negative if safety concerns supported stopping the trial early. Using Scopus, we collected citation counts through 2015 and compared citation rates according to trial outcomes.

Results

Eight tPA trials met inclusion criteria: two were positive, four were neutral, and two were negative. The two positive trials received 9080 total citations, the four neutral trials received 4847 citations, and the two negative trials received 1096 citations. The mean annual per-trial citation rates were 333 citations per year for positive trials, 96 citations per year for neutral trials, and 35 citations per year for negative trials. Trials involving other thrombolytic agents were not cited as often, though as with tPA, positive trials were cited more frequently than neutral or negative trials.

Conclusions

Positive trials of tPA for ischemic stroke are cited approximately three times as often as neutral trials, and nearly 10 times as often as negative trials, indicating the presence of substantial citation bias.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1595-7) contains supplementary material, which is available to authorized users.

Desmoteplase for Acute Ischemic Stroke within 3 to 9 Hours after Symptom Onset: Evidence from Randomized Controlled Trials

Recent studies have shown inconsistent results regarding the value of desmoteplase for treating acute ischemic stroke (AIS) when administered within an extended time window. We performed a meta-analysis to explore the value of desmoteplase in AIS treatment. The MEDLINE, EMBASE, and Cochrane Library databases were searched for randomized controlled trials (RCTs) that had evaluated desmoteplase versus placebo for AIS. The primary outcomes were intracranial hemorrhage (ICH) within 72 hours and favorable outcome at Day 90. We pooled 819 patients from 5 RCTs. Desmoteplase treatment showed a neutral effect on favorable outcome (P = 0.42) but a favorable safety profile in terms of ICH (P = 0.64) compared with the placebo group. In the subgroup analysis, 90 μg/kg desmoteplase, a late time to treatment (6–9 hours), and serious stroke symptoms at baseline (NIHSS > 12) subgroups showed high risks of ICH (P ≤ 0.02). A high dose of desmoteplase (125 μg/kg) showed a tendency to improve recanalization (P = 0.05), but was also associated with an increased risk of death (P = 0.04). In conclusion, desmoteplase administered over an extended time window had no significant effect on functional recovery but exhibited a favorable safety profile in patients with AIS.

Favorable outcome of blood urea nitrogen/creatinine-based hydration therapy 3 months after acute ischemic stroke

BACKGROUND

Dehydration is associated with acute ischemic stroke. However, the relationship between hydration therapy given during acute ischemic stroke and clinical outcomes remains unclear.

AIMS

We determined whether hydration therapy in patients with a blood urea nitrogen/creatinine (BUN/Cr) ratio of at least 15 improved clinical outcome.

METHODS

We conducted a nonblinded, phase II, single-arm, prospective study of patients with acute ischemic stroke and BUN/Cr ratio of at least 15 with historical controls. The hydration group received intravenous bolus (300-500 mL) saline followed by maintenance saline infusion (40-80 mL/h for the first 72 hours), whereas the control group received maintenance saline infusion (40-60 mL/h for the first 24 hours and 0-60 mL/h for 24-72 hours after stroke). The study end point was the percentage of patients with a favorable outcome defined as modified Rankin scale score of 2 or lower at 3 months after stroke.

RESULTS

A total of 237 patients were enrolled (hydration, n = 134; control, n = 103). The mean volume of saline infused within the first 72 hours was significantly larger (P < .001), and the rate of favorable outcome at 3 months after stroke was significantly higher (P = .016) in the hydration group than in the controls. Further analysis revealed that the difference was significant in the lacunar stroke subtype (P = .020) but not in the nonlacunar subtype.

CONCLUSIONS

Blood urea nitrogen/Cr ratio-based saline hydration therapy in patients with acute ischemic stroke significantly increased the rate of favorable clinical outcome with functional independence at 3 months after stroke.

ASPECTS (Alberta Stroke Program Early CT Score) Assessment of the Perfusion-Diffusion Mismatch

BACKGROUND AND PURPOSE

Rapid and reliable assessment of the perfusion-weighted imaging (PWI)/diffusion-weighted imaging (DWI) mismatch is required to promote its wider application in both acute stroke clinical routine and trials. We tested whether an evaluation based on the Alberta Stroke Program Early CT Score (ASPECTS) reliably identifies the PWI/DWI mismatch.

METHODS

A total of 232 consecutive patients with acute middle cerebral artery stroke who underwent pretreatment magnetic resonance imaging (PWI and DWI) were retrospectively evaluated. PWI-ASPECTS and DWI-ASPECTS were determined blind from manually segmented PWI and DWI volumes. Mismatch-ASPECTS was defined as the difference between PWI-ASPECTS and DWI-ASPECTS (a high score indicates a large mismatch). We determined the mismatch-ASPECTS cutoff that best identified the volumetric mismatch, defined as VolumeTmax>6s/VolumeDWI≥1.8, a volume difference≥15 mL, and a VolumeDWI<70 mL.

RESULTS

Inter-reader agreement was almost perfect for PWI-ASPECTS (κ=0.95 [95% confidence interval, 0.90-1]), and DWI-ASPECTS (κ=0.96 [95% confidence interval, 0.91-1]). There were strong negative correlations between volumetric and ASPECTS-based assessments of DWI lesions (ρ=-0.84, P<0.01) and PWI lesions (ρ=-0.90, P<0.01). Receiver operating characteristic curve analysis showed that a mismatch-ASPECTS ≥2 best identified a volumetric mismatch, with a sensitivity of 0.93 (95% confidence interval, 0.89-0.98) and a specificity of 0.82 (95% confidence interval, 0.74-0.89).

CONCLUSIONS

The mismatch-ASPECTS method can detect a true mismatch in patients with acute middle cerebral artery stroke. It could be used for rapid screening of patients with eligible mismatch, in centers not equipped with ultrafast postprocessing software.

Neuroimaging as a Selection Tool and Endpoint in Clinical and Pre-clinical Trials

Standard imaging in acute stroke enables the exclusion of non-stroke structural CNS lesions and cerebral haemorrhage from clinical and pre-clinical ischaemic stroke trials. In this review, the potential benefit of imaging (e.g., angiography and penumbral imaging) as a translational tool for trial recruitment and the use of imaging endpoints are discussed for both clinical and pre-clinical stroke research. The addition of advanced imaging to identify a “responder” population leads to reduced sample size for any given effect size in phase 2 trials and is a potentially cost-efficient means of testing interventions. In pre-clinical studies, technical failures (failed or incomplete vessel occlusion, cerebral haemorrhage) can be excluded early and continuous multimodal imaging of the animal from stroke onset is feasible. Pre- and post-intervention repeat scans provide real time assessment of the intervention over the first 4–6 h. Negative aspects of advanced imaging in animal studies include increased time under general anaesthesia, and, as in clinical studies, a delay in starting the intervention. In clinical phase 3 trial designs, the negative aspects of advanced imaging in patient selection include higher exclusion rates, slower recruitment, overestimated effect size and longer acquisition times. Imaging may identify biological effects with smaller sample size and at earlier time points, compared to standard clinical assessments, and can be adjusted for baseline parameters. Mechanistic insights can be obtained. Pre-clinically, multimodal imaging can non-invasively generate data on a range of parameters, allowing the animal to be recovered for subsequent behavioural testing and/or the brain taken for further molecular or histological analysis.

Therapeutic Potential of Tenecteplase in the Management of Acute Ischemic Stroke

Given that alteplase has been the only approved thrombolytic agent for acute ischemic stroke for almost two decades, there has been intense interest in more potent and safer agents over the last few years. Tenecteplase is a bioengineered mutation of alteplase with advantageous pharmacodynamics and pharmacokinetics. The superiority of tenecteplase over alteplase has been proven by in vitro and animal studies, and it was approved for use in myocardial infarction more than a decade ago. In patients with acute ischemic stroke, tenecteplase has shown promise in randomized phase II trials and the drug is currently being tested in four phase III clinical trials that will start delivering definite results in the near future: NOR-TEST (NCT01949948), TASTE (ACTRN12613000243718), TEMPO-2 (NCT02398656), and TALISMAN (NCT02180204).

Stroke- on- Awakening: Safety of CT-CTA Based Selection for Reperfusion Therapy

BACKGROUND

We studied the safety of use of acute reperfusion therapies in patients with stroke- on- awakening using a computed tomographic angiography (Cta) based large vessel occlusion-good scan paradigm in clinical routine.

METHODS

the Cta database of the Calgary stroke program was reviewed for the period January 2003-March 2010. patients with stroke-on-awakening with large artery occlusions on Cta, who received conservative, iV thrombolytic and/or endovascular treatment at discretion of the attending stroke neurologist were analyzed. time of onset was defined by the time last seen or known to be normal. Baseline non-contrast Ct scan (nCCt) alberta Stroke program early Ct Score (aSpeCtS) > 7 was considered a good scan. hemorrhage was defined on follow-up brain imaging using eCaSS 3 criteria. independence (mrS≤2) at three months was considered a good clinical outcome. Standard descriptive statistics and multivariable analysis were done.

RESULTS

among 532 patients with large artery occlusions, 70 patients with stroke-on-awakening (13.1%) were identified. the median age was 69.5 (iQr 24) and 41 (58.6%) were female; 41 (58.6%) received anti-platelets only and 29 (41.4%) received thrombolytic treatment [iV-12 (17.1%), iV/ia-12 (17.1%) and ia-5(7.1%)]. unadjusted analysis showed that baseline nCCt aSpeCtS ≤ 7 (p=0.002) and higher nihSS scores (p=0.018) were associated with worse outcomes. there were no ph2 hemorrhages in the iV thrombolytic or endovascular treated group. functional outcome was not different by treatment.

CONCLUSION

When carefully selected using Ct –Cta, by a good scan (aSpeCtS > 7) occlusion paradigm, acute reperfusion therapies in patients with stroke-on-awakening can be performed safely in clinical routine.

The use of stent retrievers in acute ischemic stroke

INTRODUCTION

Acute ischemic stroke (AIS) is one of the leading causes of mortality and adult disability worldwide. For two decades, the preferred approach for AIS was intravenous recombinant tissue plasminogen activator (IV tPA). However, IV tPA cannot be given to many AIS patients who do not meet strict criteria for its use. IV tPA has also had lesser benefit in patients with large clot burden in the context of large vessel occlusion (LVO).

AREAS COVERED

Endovascular stroke therapy had been an 'unproven' therapy despite numerous trials of intra-arterial pharmacologic thrombolysis and mechanical thrombectomy. With the advent of stent-retriever devices, there has been a paradigm shift in the utilization of endovascular therapies for AIS. Our review discusses cerebrovascular hemodynamics, the basis of the recanalization models in AIS, aspects of intravenous thrombolysis, prior generations of endovascular therapy, and the recent successful AIS stent retriever trials. Expert commentary: Recently 'stent-retrievers', a new generation of mechanical thrombectomy devices, were shown to be associated with improved functional outcomes in AIS secondary to proximal intracranial anterior circulation LVO. Stent retrievers are a major advance in AIS care and will have significant impact on the evolution of stroke systems of care.